The pedestrians had stopped to check out a Tesla parked on Canfield between Second and Cass when the accident occurred at about 5:20 p.m., said Detroit police spokesman Officer Dan Donakowski. The area is near the popular businesses Shinola, Traffic Jam & Snug and Third Man Records.

Detroit police spokesman Sargeant Adam Madera said the two other victims, a 45-year-old female and a male of unknown age, remain in serious condition.

The truck also hit a fourth person who didn't need to go to the hospital.

The Tesla was part of the Tesla Explores event, a mobile gallery travelling throughout North America to showcase vehicle options. The event was slated to run through June 11, but has been canceled after news of the accident, according to a Tesla official.

Donakowski said police are investigating whether the driver was under the influence of alcohol or drugs.